Association between ageing men's progressive falling of circulating androgen levels and ED is not clearly demonstrated. The analysis of all what have been written about this subject clearly proves that an androgenomodulation of erectile function exists. Indeed, the androgens seem to have an action on penile tissue innervation, on the structure and function of penile trabecular smooth muscle, on the penile endothelial function, as well as on the fibroelastic properties of the penile corpus cavernous. The addition of testosterone improves a great number of androgen deficiency in the aging male (ADAM). Recent studies demonstrated that all hypogonadal patients cannot successfully benefit of phosphodiesterase type 5 (PDE5) inhibitors. With these patients, the prescription of testosterone replacement therapy may improve the response of PDE5 inhibitors.